Polychlorinated dibenzothiophenes (PCDTs) are a class of compounds structurally similar to dioxins that possess various toxicological impacts on living organisms. Unfortunately, information on the levels of PCDTs in freshwater lakes in China is still scarce. In this work, the occurrence of 14 congeners of PCDTs in different matrices (i.e., sediment, suspended particulate matter (SPM), and water) of Chaohu Lake was investigated. It was determined that the concentrations of 14 PCDTs (Σ14PCDTs) in the sediment, SPM, and surface water were 0.40-3.55 ng g-1 (dry weight, d.w.), 0.38-2.95 ng?g-1 d.w., and 0.34-2.61 ng L-1, respectively. The dominant congener found in sediments was 1,2,3,4,7-penta-CDT (19.54%), and 1,3,9-tri-CDT was the predominant congener in SPM (19.13%) and water (20.08%). Medium- and high-chlorinated PCDTs were detected as the major compounds in sediments and SPM. The low-chlorinated PCDTs (e.g., mono-CDTs) have higher relative percentages in the water than those detected in the sediment samples. The annual Σ14PCDT input of the eight main tributaries to Chaohu Lake was 19.90 kg. A strong linear correlation between the Σ14PCDT levels and the organic carbon (OC) content demonstrated that OC had an important influence on the PCDT redistribution in Chaohu Lake. In addition, the organic carbon normalized partitioning coefficient (logKOC) of PCDTs in the SPM-water system in Chaohu Lake was 1.95-2.49 mL g-1, and correlations between logKOC and other typical environment-related properties of PCDTs were established. This study provided useful data on the evaluation of ecological risks of PCDTs in Chaohu Lake.Biodegradation is responsible for most contaminant removal in plumes of organic compounds and is fastest at the plume fringe where microbial cell numbers and activity are highest. As the plume migrates from the source, groundwater containing the contaminants and planktonic microbial community encounters uncontaminated substrata on which an attached community subsequently develops. While attached microbial communities are important for biodegradation, the time needed for their establishment, their relationship with the planktonic community and the processes controlling their development are not well understood. We compare the dynamics of development of attached microbial communities on sterile substrata in the field and laboratory microcosms, sampled simultaneously at intervals over two years. We show that attached microbial cell numbers increased rapidly and stabilised after similar periods of incubation (?100 days) in both field and microcosm experiments. These timescales were similar even though variation in the contaminant source evident in the field was absent in microcosm studies, implying that this period was an emergent property of the attached microbial community. 16S rRNA gene sequencing showed that attached and planktonic communities differed markedly, with many attached organisms strongly preferring attachment. Successional processes were evident, both in community diversity indices and from community network analysis. Community development was governed by both deterministic and stochastic processes and was related to the predilection of community members for different lifestyles and the geochemical environment.Estuarine sediment denitrification and anammox in response to increased nitrogen (N) loads remain poorly understood. In this study, we used N isotope tracer approach to investigate the spatial distribution of denitrification and anammox and identified the crucial controls on the partitioning of dinitrogen gas (N2) production along the Min River Estuary (MRE), a highly impacted estuary in southeast China. The results indicated that denitrification and anammox rates ranged from 10.5 to 70.7 nmol g-1 h-1 and from 0.44 to 4.31 nmol g-1 h-1, respectively. Relative contribution of anammox to N2 production (Ra) was in a range of 1.04-15.1%, tending to increase toward estuary mouth. Denitrification rates were significantly higher in upper (high N loads) than in lower estuary (low N loads), while anammox rates and Ra showed inverse distributions along the MRE. Wastewater discharge caused the N point pollution triggering denitrification but inhibiting anammox. The best predictor of the variations in denitrification rates was total nitrogen, whereas pH and NH4+ could explained the variations in anammox rates across the estuary. The crucial predictors for the partitioning of N2 production between denitrification and anammox were NH4+ and NOx-. https://www.selleckchem.com/products/u18666a.html These results suggest that the increase in human activities intensity can alter the partitioning of N2 production between denitrification and anammox, and the magnitude of this switch can be predicted by N loads in MRE and other highly impacted estuaries.Vesicular monoamine transporter 2 (VMAT2) has been associated with the risk of PD. Genetic reduction of VMAT2 level is reported to increase the vulnerability for dopaminergic neurodegeneration. In this study, by using in vivo microPET imaging with a VMAT2 radioligand [F]fluoropropyl-(+)-dihydrotetrabenazine ([F]FP-(+)-DTBZ), we investigated the enhanced role of inhibiting VMAT2 in 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced loss of dopaminergic neurons.
The (+)-α-dihydrotetrabenazine ((+)-DTBZ, an inhibitor of VMAT2, 5mg/kg), or MPTP (low dose (ld) 10mg/kg, high dose (hd) 30mg/kg) or both of them were intraperitoneally injected into C57BL/6 mice for 5 or 10 consecutive days. MicroPET imaging with [F]FP-(+)-DTBZ was performed to test the dopaminergic neuronal integrity. [F]FP-(+)-DTBZ uptake in striatum was quantified as standardized uptake value (SUV). The pathological changes in the striata and substantia nigra were confirmed by measuring the DA contents and immunohistochemical st related to the pathogenesis of PD and tracing VMAT2 activity with PET imaging is of potential value in monitoring PD progression.
MicroPET brain imaging with [18F]FP-(+)-DTBZ noninvasively revealed that (+)-DTBZ co-administration significantly aggravated the neurotoxicity of MPTP to dopaminergic neurons, suggesting that inhibition of VMAT2 may be related to the pathogenesis of PD and tracing VMAT2 activity with PET imaging is of potential value in monitoring PD progression.